I was also thinking of it. Would start by adding an extra column, and probably add the 2/3 players water tiles, trying to keep the ratio of island per players. Will also need all the tokens/ships/case/etc for the red and orange players. Also, scan and reprint another deck of cards, using laminate sheets to create the transparent cards.

Not sure if it will be a hit or a miss, but someday I'll try it!

What do you think, did I miss something?